Septic companies in San Rafael, CA

What the ground in San Rafael is like

The USDA soil survey rates mapped ground in San Rafael for septic drain-field suitability across roughly 17 square miles. About 100% of the rated ground is classed "Very limited", the survey records severe restrictions for a conventional drain field across most of that ground.

In San Rafael, the leading limit is slope: the ground falls steeply enough that a level trench line is hard to hold. A drain field has to sit across the grade without concentrating flow downhill; on steeper parcels that layout gets tighter. The survey flags that limit on about 95% of the rated ground here.

The limiting features the survey records most often here:

• Slope95.3%
• Depth to bedrock95.3%
• Seepage, bottom layer72.3%
• Slow water movement22.6%

This is survey data for mapped areas, not a substitute for a site evaluation on your own lot. Conditions on a single parcel can differ from the map.

USDA NRCS SSURGO, ENG Septic Tank Absorption Fields · 100% Very limited · Slope · 24 map units · 16.59 sq mi · read 2026-08-30